Question

用递等式计算（能简算的要用简便方法计算） 2.5×1.25×8 &nb...

用递等式计算（能简算的要用简便方法计算） 2.5×1.25×8 9.7+22.78÷3.4 79.8÷5.7-4.5 0.86+0.86×99 8.6+1.4-5.26+1.74 （52-7.2÷3.6）×0.25．

Answer 1

①2.5×1.25×8
=2.5×（1.25×8）
=2.5×10
=25

②9.7+22.78÷3.4
=9.7+6.7
=16.4

③79.8÷5.7-4.5
=14-4.5
=9.5

④0.86+0.86×99
=0.86×（99+1）
=0.86×100
=86

⑤8.6+1.4-5.26+1.74
=（8.6+1.4）-5.26+1.74
=10-5.26+1.74
=4.74+1.74
=6.48

⑥（52-7.2÷3.6）×0.25
=（52-2）×0.25
=12.5